Adobe has issued a new patch which fixed nineteen vulnerabilities in Flash. This update addresses some critical issues which could potentially allow hackers to take control of an affected system. One of the vulnerabilities (CVE-2015-8651) is already being used by hackers in limited, targeted attacks.

Well afaik HTML5 is already better in nearly every single way and is more compatible with more content since its a universal standard. Besides like you said the constant patching of huge vulnerabilities is really awful and just tells you a lot about it